The large tilt requirement into HEPI for the TMS tilting really accentuated the IPS sensor noise when the HEPI loop was open.  The HEPI had not been commissioned so the tilt was direct drive.  On Friday Jim, Fabrice and I closed those loops and I did my best to restore the previous tilt to the system.  We only got to within ~25urads cause the other loop closings caused more drive to the the V1 corner pushing the IPS to 29900counts with a watchdog trigger at 30000.

See the attached 8 day plot.  The plot shows lots of things but mainly look at the lower right graph with T240 INMON.  The first half of the plot is before the hepi position loops were closed.  The quieter interval in the middle left, was during a noise study and we had no tilt (see the various hepi graphs).  In the middle of the time frame we closed the ETMX HEPI position loops and you see the T240 channel go very quiet.  There are no railing spikes that would have tripped the ISI.  On Monday, Keita offloaded much of the HEPI tilt to the TMS because the HEPI IPS was close to its trip level and TMS needed a little bit more tilt.  You can see the HEPI tilt change in the channel 9 & 12 graphs.  However, there is no change in the noise at the T240 when Keita offloaded HEPI to TMS (I zoomed in and there is no difference in the time series view.)

Bottom line, The HEPI tilt will not cause ISI trips with the HEPI position loops closed.  HEPI could take much of the TMS tilt back if needed.

Wrote and installed the code for running the ring heaters.
Added the rough calibration values that Aidan B had recommended for running the ring heaters.

Some data below:
Upper:
Requested Power = 1.00 Watts
Requested Current = .17 Amps
Measured Voltage = 6.85 Volts
Measured Current = 0.16 Amps 
Calculated Power = 1.13 Watts
Calculated Resistance = 42.81 Ohms

Lower:
Requested Power = 1.00 Watts
Requested Current = 0.17 Amps
Measured Voltage = 6.71 Volts
Measured Current = 0.17 Amps 
Calculated Power = 1.11 Watts
Calculated Resistance = 39.47 Ohms

A quick, back-of-the-envelope calculation shows that the ring heaters are working properly. Although their values are a bit different than ITMY shown in ALOG 8816, this is mostly due to only being roughly calibrated.  The next step is to do a long term 4+ hour test to show curvature change and robustness. 

10:51 I restarted the h1slow-cds epics gateway due to Beckhoff IOC work.

Koji and I will be in the PSL today for replacing IO_MB_M2 as a preparation of the high power laser.

Please do not change the PSL piezo alingment and MC1/2/3 DC biases because they are our alignment references.

All models have stopped on h1seih45 at 1073754093, having suffered an ADC timeout.  It's possible that the timing fiber was disconnected for work, not sure of the cause.  I am going to reboot the computer after removing it from the dolphin network.

I started working on the arm cavity alingment this morning, we have flashes of 400 counts on the transmitted PD (ALS COMM), the refl PD drops from 19500 to 19000, and a spot is clearly visible on the ETM camera (scren shots attached). This can sort of lock for a few seconds.  I'm heading to the X end to look at the locking. 

Also. MC1 misalinged so we can see green on the ITM without confusion from the IR. 

[Stefan, Kiwamu]

We are now in the process of checking/adjusting the suspensions as our length actuators.

• We adjusted the L2P balance in the M1 stage of PRM and PR2.
  • This was done by applying a big offset in the LOCK L filter of the M1 stages and corrected the L2P by putting a non-zero gain in their DRIVEALIGN L2P.
  • As for PRM, we simply looked at the REFL camera and adjusted the L2P such that the beam doesn't move with the length offset.
  • As for PR2, because we didn't have an intuitive sensor, we adjusted it by looking at REFL_DC when PRX is locked.
  • This eventually allowed us to offload low frequency feedback to the M1 stages. Because the M1 stages take care of low frequencies below 1 Hz, we don't have to an L2P adjustment at high frequencies.
  • H1:SUS-PR2_M1_DRIVEALIGN_L2P_GAIN = 0.0045
  • H1:SUS-PRM_M1_DRIVEALIGN_L2P_GAIN  = 0.006
     
• PRM crossover frequency was measured to be approximately 10 Hz (see the attached).
  • M2 gain was at 0.2.
• We then locked PRY and actuated on BS to see how the length transfer function looks like.
  • The UGF was set to be about 10 Hz by lowering the gain so that the control doesn't suppress BS's length signal at high frequencies.
  • Only FM6 of M2 LOCK FILTER in BS was enabled to make the entire transfer function look more like a pendulum, namely 1/f^2.
  • Indeed the length transfer function was 1/f^2 above 10 Hz and looked good (see the attached).
• Also, we copied the filters for the BS oplev loops over from the L1 to H1 directory.
  • The pitch loop looked helpful in the sense that it reduced the RMS of the motion.
  • The yaw loop may not be necessary at this point because the dominant disturbance seems mainly at 0.2-ish Hz which is out of the oplev control band.
  • For now, we leave the yaw loop off as it doesn't look doing something useful at this point. (Though we probably will need it when we use BS to lock the Michelson.)

One thing I am confused at this moment is the length transfer function of PRM and PR2. I did the same TF measurement as for the BS length drive for comparison, and found that the TF were 1/f above 10 Hz rather than 1/f^2 (see the attached). There must be some stupid reason because otherwise we wouldn't be able to lock PRX or PRY. I will revisit this issue tomorrow.

[Dick, Daniel, Koji]

The POP 2f demodulator unit previously installed on row 28 of the ISC R2 rack (c.f. this entry ) was replaced with the 2f demod unit.
This unit has a 24MHz LPF and a 80MHz HPF on CH1 and CH2, respectively, forming a diplexer configulation for 18MHz (2xf1) and 90MHz (2xf2) signals.
Therefore, the temporary power splitter for the POP 2f path was removed.

Because of this action, we expect that the demod phase for the POPAIR18 and POPAIR90 were changed.

The 3f demods (CH3/4) still have the power splitter. This will be removed when the 3f diplexer unit is installed on row 27.

We also cleaned up some of the RF cables:

- The REFLAIR9 cable plugged on row 34 is now routed through the patch panel on row 27.
This means that the demod phase of the REFLAIR_A_RF9 was changed.

- The cable for REFL9 was made and connected to the demodulator on row 34.

- Unnecessary connectors/cables were removed from the patch panel on row 29.

   Last set of TFs on H1-SR2 showed a longitudinal to yaw cross coupling at 1.51 and 2.77Hz. I adjusted the Coil Holder and recentered the BOSEMs.
 
   There were only two of the four Coil Holder Mounting Brackets installed, (which may be a source of the noise in this suspension and a contributor to the cross coupling) when the earlier TFs were taken. The missing two Mounting Brackets required modification due to misaligned mounting slots. These modifications were not completed in time to be installed on the suspension before it was moved to the LVEA. One of the Mounting Brackets was modified correctly; and has been installed on the suspension. The second Mounting Bracket was not modified correctly and will need to be reworked before it can be installed. Three of the four Mounting Brackets are now clamping the Coil Holder to the Weldment. 

   I have started a new set of TFs on H1-SR2, to see if the BOSEM adjustment and the addition of the third Mounting Bracket will improve the performance of the suspension over that revealed in the earlier TFs.